Peel and chop the onion. Celery and potato peel, wash and also dice. Fry everything in the pot in 1 tbsp. hot oil. Add 3/4 l water and broth. Bring to the boil, cover and simmer for about 20 minutes
Cut the toast into cubes. Fry in 1 tbsp. hot oil until golden brown. Wash the thyme, shake dry and pluck
Finely puree the soup with the cutting stick. Add thyme and bring to the boil again. Melt cheese in flakes in it. Stir in cream. Season to taste with salt and pepper. Sprinkle with croutons
Large celery tubers are easier to peel if you cut them into thick slices beforehand. You can also season the celery cream soup with nutmeg, mustard or horseradish. For crôutons, in addition to fine toast bread, more rustic breads are also suitable, e.g. rye mix or wholemeal bread